1. FIELD OF THE INVENTION
The present invention relates to a covered arc welding electrode. More specifically, the invention relates to a covered arc-welding electrode which can form a superior crack-resisting weld zone even if a base metal, such as an established steel bridge, an ocean structure or the like, is welded while fluctuating stresses are continually applied to the base metal.
2. DESCRIPTION OF THE PRIOR ART
While vehicles and so forth pass over a bridge, fluctuating stresses are continually applied thereto. When welding a structure under operating conditions for repair or rebuilding, small cracks are often generated immediately after welding it since tension and compression are continually applied thereto while the weld metal is still at a high temperature and is therefore brittle. Afterward, these small cracks can serve as the starting points from which larger cracks may grow and cause the life of the bridge to become shorter.
When conventional covered arc welding electrodes are used, traffic on the bridge or the like must be restricted while welding is performed or the weld zone must somehow be stationarily fixed prior to welding. Otherwise, unless other fastening means are employed, the generation of cracks is considered to be inevitable and a shortened functioning life of the structure must be anticipated.